This blog provides updated forecasts and comments on current weather or other topics

Thursday, April 18, 2013

Summer in April

Warm, dry weather will be returning next week, with temperatures climbing to near 70F by Wednesday. The models have been going for a major warm spell for a while and now there is little doubt it will happen. But first we need to get through the next few days.

During the next 48-h, a few weak troughs in westerly flow will move through (see upper level--500 hPa--chart for Friday afternoon). The result will be fairly substantial precipitation over the

mountains during the period, with lesser values over the western lowlands (and even less east of the Cascade crest). Take a look at the 48-h precipitation ending 5 PM on Saturday. 2-5 inches over the western slopes of the Cascades, but little along the eastern slopes of the Cascades. Snow in the higher passes. Also notice that Kitsap is relatively dry...the result of descent off the Olympics.

Sunday is the transition day--the beginning of the drying and warming. By Monday morning, the upper trough is way to our east and substantial ridging has developed over the eastern Pacific (see map). Get your sunglasses! Stock up on plants and fertilizer.

By Wednesday morning the ridge has amplified...this will bring warming temperatures and sunny skies.

The ridge strengthens further by 5 PM on Thursday (see below). You don't need to be a meteorologist to know what this means.

The implications of these forecasts is that precipitation will end for most of you by mid-day Sunday and skies will clear. Temperatures will edge up into the lower 60s on Monday to upper 60s to low 70s on Wednesday and Thursday. I checked the the gold-standard European Center forecast for Thursday at 5 PM---same story. Here is the surface air temperature prediction from the EC. It is going for 68-75 over the western lowlands and warmer in the Willamette Valley and parts of eastern WA.

And if that is not exciting enough, take a look at the 8-14 day temperature forecast from the Climate Prediction Center. High probability of above normal temperatures over the entire western U.S.

To repeat something I have said before in this blog...this spring does not look like a repeat of the past two, which were cold and wet. We are enjoying a fairly normal spring...for a change.